This invention relates to an adhesive tape that can be used to releasably adhere an insert to a page of a multi-page publication such as a newspaper or a magazine in such a way that when the insert is removed from the page of the printed publication, the surfaces of both the page and the insert are not tacky and the page does not get damaged by removing the insert.
Inserts such as product samples and mail back cards are frequently inserted in newspapers or magazines. Such inserts can be inserted in a magazine by permanently adhering them to a page of the multi-page printed publication. However, this has the disadvantage that upon removing the insert from the multi-page printed publication, the page to which it was adhered may get damaged. It is also known to adhere the insert to a page of a magazine or newspaper by means of a repositionable adhesive. While this method does not create damage to the page to which the insert was adhered, either the page or the insert will contain adhesive and one of them will remain tacky.
Similarly, U.S. Pat. No. 4,398,985 describes that it is known to coat a face stock with a release material and this is then laminated, with the release coated side down, to a paper base which has been coated on both sides with pressure sensitive adhesive. The outer adhesive layer is then used to adhere the face stock to a substrate. Due to the release material, the face stock can be peeled away from the adhesive layer of the paper base and thus the face stock can be separated from the substrate. However, the substrate remaining will be tacky due to the adhesive remaining thereon. Accordingly, this type of construction is not suitable for placing inserts in a magazine or printed publication.
U.S. Pat. No. 4,398,985 attempts to solve this problem by providing a self-detackifying adhesive laminated construction. The laminated construction is produced by coating a film of a non-silicone containing polymer onto one side of a face stock and then laminating this construction to an adhesive which has been coated on a release liner. The polymer film and adhesive have differential release capabilities such that the polymer film will initially adhere to the face stock and the adhesive layer on the other side thereof, but upon delamination, the polymer film will have greater affinity for the adhesive layer. Accordingly, when the face stock is peeled away, the polymer film will delaminate therefrom and remain permanently affixed to the adhesive coating. This results in a non-tacky surface remaining because the remaining adhesive coating is covered by a non-tacky polymer. Also, the face stock will not be tacky.
While, the above method may be effective in placing inserts in magazines, it suffers from several disadvantages. Firstly, the method requires that the insert be coated on one side with a polymer film. This is not very practical in many instances. For example if the insert concerns a mail back card that is printed on one or both sides, after printing, the printer might have to send the mail back card to a specialised service for coating the mail back card and laminating it to the release liner with adhesive, because often printers do not have the necessary equipment. This makes the process cumbersome and costly. Moreover, in producing magazines, printers are often under serious time constraints which do not allow for the insert to be send to a specialised service to coat and laminate the insert. Also, depending on the kind of surface of the insert, for example paper or plastic, different polymer film coatings will be needed due to the required differential release capabilities.
EP 414 538 discloses a card that is adapted for removable attachment to a surface. The card comprises a card sheet having two opposite sides and a laminated sheet bonded to one side of the card sheet. The laminated sheet includes a plurality of overlying layers that are adapted to separate along an interface between two layers of thin film. The interface comprises a layer of adhesive. Accordingly, when the card sheet is removed by delamination at the interface, at least one of the remaining surfaces will contain the adhesive.
U.S. Pat. No. 4,721,638 discloses a sticking material for preventing resticking. The material has an adhesive layer, a second layer laminated on one main surface of the adhesive layer, a peeling agent layer laminated on the second layer and a first layer laminated on the peeling agent layer. The equation, a less than b is satisfied, wherein the force required to separate the first layer from the second layer at the peeling agent layer is denoted as a, and the adhesive force of the adhesive layer with the surface of the second layer is represented by b. Since the second and first layers are adhered temporarily via the peeling agent layer, the first layer once separated from the second layer, cannot be restuck. While this material is useful for labels such as price tags, the material is however not suitable for placing inserts in a multi-page printed publication.
U.S. Pat. No. 4,925,714 discloses a co-extruded core laminate of polypropylene and polyethylene which has been provided on both sides with an adhesive layer. According to the teaching of this patent, such an adhesive tape can be used to adhere coupons, cards, tags or other cut-to-shape face pieces on substrates such as containers, wrappings and packages. The face piece can subsequently be peeled off in such a way that both the bottom of the face piece and top of the substrate are non-tacky. This is accomplished by delamination that occurs between the co-extruded layers. Such an adhesive tape however has the disadvantage that the bottom of the face piece and top of the substrate are not writable. Further, the composition of the co-extruded layers of the core laminate are limited in composition and cannot for example contain thermo-sensitive materials and components that degrade at the temperatures needed in an extrusion process.
The present invention provides an adhesive tape (10,20) for laminating a first substrate (31) to a second substrate (32), said adhesive tape comprising a carrier (13) having on a first major surface a first adhesive layer (12) and having on a second major surface opposite to said first major surface in the order given a non-tacky polymer layer (14) and a second adhesive layer (15), wherein said adhesive tape (10,20) is capable of being adhered to said first substrate (31) by said first adhesive layer (12) and to said second substrate (32) by said second adhesive layer (15), and said adhesive tape (10,20) being capable of delamination between said carrier (13) and said non-tacky polymer layer (14) when said first (31) and second substrate (32) are peeled away from each other so as to leave said carrier (13) on said first substrate (31) and said non-tacky polymer layer (14) on said second substrate (32) with a major surface of said non-tacky polymer layer (14) or said carrier (13) exposed, with the proviso that said non-tacky polymer layer (14) and carrier (13) are not co-extruded layers.
The adhesive tape of the present invention allows one substrate to be releasably adhered to another substrate. When one of the substrates is peeled from the other, the adhesive tape delaminates between the carrier 13 and the non-tacky polymer layer 14 such that the surface on both substrates is non-tacky. Moreover, both surfaces can be chosen such that one or both of them are writable. This is particularly interesting in cases where for example the insert is a mail back card that has to be completed with information from the user. Further, the composition of carrier 13 and non-tacky polymer layer 14 can be varied widely and any of carrier 13 or non-tacky polymer layer 14 can include components that are thermo-sensitive and/or that might degrade at substantially elevated temperatures normally needed in an extrusion process. Also, the adhesive tape of the present invention has the advantage that the complete process of placing inserts in a multi-page printed publication can be automated and the adhesive tape can be used by a conventional printer without the need for a specialized service.
In a particular embodiment of the present invention there is provided an adhesive tape (10,20) for laminating a first substrate (31) to a second substrate (32), said adhesive tape comprising a carrier (13) having on a first major surface a first adhesive layer (12) and having on a second major surface opposite to said first major surface in the order given a non-tacky polymer layer (14) and a second adhesive layer (15), wherein the following formula is satisfied:
A greater than C less than B
wherein A is the force necessary to peel said first adhesive layer (12) from said carrier (13), B is the force necessary to peel said second adhesive layer (15) from said non-tacky polymer layer (14), and C is the peel force necessary to peel the non-tacky polymer layer (14) from said carrier (13) to expose a major surface of said non-tacky polymer layer (14) or said carrier (13), with the proviso that said non-tacky polymer layer (14) and carrier (13) are not co-extruded layers. As explained in more detail below, the peel force C can be adjusted by including a delamination control layer 17 between carrier 13 and the non-tacky polymer layer 14.
The present invention also provides a method for releasably adhering a first substrate (31) to a second substrate (32) using an adhesive tape as described above.
Further provided is a laminate comprising a first substrate (31) releasably adhered to a second substrate (32) by an adhesive tape (10,20) as described above.
The present invention also provides a method of manufacturing an adhesive tape (10,20).